package part1;

public class Projector {
    private static final Projector INSTANCE = new Projector();

    public static Projector getInstance() {
        return INSTANCE;
    }

    public void on() {
        System.out.println("投影仪打开了");
    }

    public void off() {
        System.out.println("投影仪关闭了");
    }
}
